As an electric toothbrush with a cleaning head making a reciprocating linear motion, a motor-powered electric toothbrush including conversion means that converts rotation of a pinion fixedly attached to a rotation shaft of a motor into rotation of a face gear about an axial core orthogonal to the rotation shaft and then converts the rotation of the face gear into reciprocating linear motion of a drive shaft via a crank shaft, is widely employed because of its low-cost manufacturability. However, in the motor-powered electric toothbrush, the face gear is rotated at a reduced speed by engagement of gear wheels, and thus the cleaning head is set with a vibrational frequency of 1,500 to 5,000 cpm and an amplitude of 3 to 7 mm, whereby there is a limit for providing the cleaning head with a high vibrational frequency. Accordingly, so-called sonic electric toothbrushes having a cleaning head with a vibrational frequency of 5,000 to 11,000 cpm and an amplitude of 0.2 to 1.0 mm, have recently been suggested and put into practical use, in which a plurality of gears is combined (refer to Patent Document 1, for example), a scotch yoke mechanism is used (refer to Patent Document 2, for example), or a linear actuator having a permanent magnet and a coil is used (refer to Patent Document 3, for example).
Meanwhile, as an oral cavity cleaning device, there is put into commercial use a water flow type oral cavity cleaning device including a pump capable of discharging a cleaning liquid by reciprocating linear motion of a piston; pump drive means driving the piston; and a discharge nozzle for the cleaning liquid, in which the cleaning liquid can be intermittently injected from the nozzle to thereby efficiently clean interdental gaps and periodontal pockets with the cleaning liquid (refer to Patent Document 4, for example).
In addition, as a water flow type oral cavity cleaning device, there is suggested a water flow type oral cavity cleaning device in which a connection member capable of being connected to a drive shaft of a drive unit of a motor-powered electric toothbrush is provided so that a pump can be driven by the drive unit of the motor-powered electric toothbrush, whereby pump drive means of the water flow type oral cavity cleaning device can be used also as a drive unit of a motor-powered electric toothbrush (refer to Patent Document 5, for example).